1. Field of the Invention
This invention relates to a sewing machine in which a thread is caught below a needle plate to be cut by a cutting blade.
2. Description of the Related Art
Conventional sewing machines comprise a thread catcher provided to be reciprocally moved below a needle plate. The thread catcher is moved so as to pass through a thread loop, whereby the thread loop is divided by the thread catcher. The thread catcher catches the thread during its return movement. The caught thread is moved to the cutting blades to be cut. Japanese Patent No. 2871201 granted to the assignee of the present application discloses such a thread cutting manner. In the aforesaid conventional sewing machine, a moving blade 510 serving as the thread catcher and a fixed blade 520 comprise respective horizontally extending plate-like members, as shown in FIG. 42. The thread is divided by the fixed blade 520. A thread amount of a thread end at a cloth side in a sewing bed depends upon the location of a needle hole of the needle plate, the location of the fixed blade 520, the location of a bobbin for a bobbin thread, a rotational locus of a thread seizing beak of a horizontally rotating shuttle, etc. A thread amount of a thread end at a needle or bobbin side also depends upon these factors.
However, there is a possibility that the thread end at the cloth side may be entangled in the sewing bed when a thread amount of the thread end at the cloth side is larger upon thread cutting. In order that the thread end at the cloth side may be prevented from being entangled, the fixed blade is moved forward to be fixed at a position so that a thread amount of the thread end at the cloth side is reduced after thread cutting. In this case, however, a thread amount of the thread end at the needle side is reduced such that an amount of thread for subsequent sewing after thread cutting becomes short. Accordingly, in the conventional sewing machines, the thread ends at the cloth and needle sides cannot be maintained in suitable amounts after thread cutting, respectively.
Therefore, an object of the present invention is to provide a sewing machine in which both thread ends at the cloth and needle sides can be maintained in suitable amounts after thread cutting, respectively.
The present invention provides a sewing machine comprising a needle plate having a needle hole through which a sewing needle is allowed to pass, a thread catcher reciprocally moved forward and backward below the needle plate and being elongated in a moving direction, the thread catcher having a frontward end with respect to a direction of forward movement of the thread catcher and including first and second generally hook-shaped catching portions, the first catching portion being located nearer to the frontward end of the thread catcher than the second catching portion with respect to the moving direction of the thread catcher during forward movement of the thread catcher, the first catching portion being further spaced from and located nearer to the needle hole of the needle plate than the second catching portion with respect to a direction perpendicular to the moving direction of the thread catcher, and a cutting blade located between the first and second catching portions at least during backward movement of the thread catcher to cut a thread caught between the first and second catching portions. In this construction, the thread catcher is moved backward so that the thread caught between the first and second catching portions intersects the cutting blade.
In the foregoing sewing machine, the first and second catching portions of the thread catcher are located at different positions with respect to the direction in which the thread catcher is moved forward. Accordingly, when the thread caught by the first and second catching portions is cut by the cutting blade, two parts of the thread cut have respective suitable lengths.